Air conditioners of the conventional type are generally electrically operated, having a fan, an evaporator coil containing a refrigerant, a compressor, condenser coil, an expansion valve for determining the refrigerant evaporating temperature, a thermostat, and an electrical control circuit. This type of equipment is normally enclosed within a rectangular cabinet. The dimensions of the cabinet are usually defined to provide an installation of the unit in a standard window opening, whereby the air from outside is forced through the evaporator coil and within the room. Other models of cabinet are designed for a permanent installation through a wall of a building.
Although the field of air conditioners is a mature art, and the efficiency of most commercial units is undisputable, the selling price of an air conditioner is not affordable by all. Likewise, it is not every home which has a window of proper dimensions to receive an air conditioner, and it is not every home owner who is willing to install a unit permanently through a wall of an apartment.
For those exceptions, relief from warm weather is generally obtained from fans which induce air movement and promote evaporation of moisture at the skin surface, providing thereby a cooling effect. Notwithstanding the fact that fans lessen the discomfort from warm weather, the air conditioner is a long leap ahead in controlling the temperature of an apartment. Unfortunately, the nature of the refrigerant remains a primary obstacle in reducing the cost of an air conditioner to please a larger number of users. The need for a compressor and evaporation equipment adds to the complexity and the selling price of those appliances.
Cold water from a house plumbing system is an abundant source of refrigerant. The cold water generally comes from deep in the ground where the temperature is relatively constant despite the warmth of the season.
Water is also priceless and nonperishable. Aside from the cost of pumping and treating it, water follows the natural cycle of evaporation and rain to recover its full properties and static energy. There are many homes in rural areas which pump their water from individual wells and where the filtering and treating of water is not needed. There are still numerous municipalities which do not treat their water either, and where the cost of pumping it is reduced from a gravity fed reservoir. For all these applications, cold water from a house's piping system is an attractive refrigerant to reduce the temperature of air passing through a fan.